I am overlaying a polygon layer with shapes representing cities over a 0.5 x 0.5 km shapefile grid. Each grid cell has an associated GDP value representing the entire GDP of said grid cell.
The workflow as I'm thinking through it would go something like this:
- Calculate percentage of coverage of overlayed city polygon layer for each grid cell
- Multiply percentage of coverage by associated grid value
- If city polygon is overlayed over multiple grid cells, add all values based on percentage of each associated grid cell coverage
- Append GDP to existing city polygon layer
Grid cell 1 = 10
Grid cell 2 = 30
City polygon 1 = 25% coverage of grid cell 1; 15% coverage of grid cell 2
City polygon 2 = 50% coverage of grid cell 1
City polygon 1 GDP = (0.25x10)+(0.15x30) = 2.5 + 4.5 = 7.0
City polygon 2 GDP = 0.50x10 = 5.0
For reference, the data I'm using is sourced from a paper conducting research on gridding global GDP based on SSP scenarios.
Another similar dataset is from SEDAC.
I have already tried the overlap analysis tool. Main issue I'm running into is not distinction between city polygons if overlaid on one grid cell since the overlap analysis tool only gives one percentage and one area per grid cell